Tool retainers for punch presses are well known in the art. Typically, the retainer is a metal block that carries a tool (e.g., a punch or die). The tool held by the retainer normally extends away from the retainer block toward a workpiece (e.g., a piece of sheet metal) to be punched or formed. The retainer block is usually secured to a mounting plate of the punch press. Thus, the retainer block interconnects the tool and the press, and enables the tool to be accurately positioned.
Tool retainers are preferably adapted to carry tools in a removable manner. For example, the workpiece-deforming surfaces of punches and dies wear down after repeated use. Thus, it is necessary to periodically remove such tools for sharpening. Toward this end, prior art retainers have been provided with ball locks that allow repeated removal and replacement of punches or dies. Reference is made to U.S. Pat. No. 2,160,676 (Richard), U.S. Pat. No. 2,166,559 (Richard), and U.S. Pat. No. 3,176,998 (Parker). The entire contents of these patents are incorporated herein by reference.
Ball locks characteristically comprise a retainer block in which two elongated bores are formed. One of the bores is adapted to receive the shank of a punch or die. This bore typically extends from near the back wall (which is typically secured to a mounting plate of the punch press) of the retainer block to the front wall of the retainer block, where such bore opens through the front wall of the retainer block. A second bore formed in the retainer block houses a spring-biased ball. This second bore extends at an angle, relative to the axis of the shank-receiving bore, from near the back wall of the retainer block to a point of intersection with the shank-receiving bore. The second, angled bore opens into the shank-receiving bore at this intersection point.
The shank of a standard ball-lock tool characteristically has a tapered recess that can be lockingly engaged by the ball in a ball lock. When the shank is operatively positioned within the shank-receiving bore, the tapered recess on the shank is aligned with the intersection point of the angled bore and the shank-receiving bore. The spring in the angled bore urges the ball toward the tapered recess on the shank. With the shank so positioned, the spring-biased ball engages the recess on the shank, thereby securely holding the tool in position. That is, the spring causes the ball to be pushed toward, and maintained in, a position where the ball is effectively trapped between the tapered recess of the shank and the interior surface of the angled bore.
It would be advantageous to provide ball-lock insert assemblies adapted for mounting in customer-manufactured holder plates. That is, it would be desirable to provide discrete ball-lock inserts that could be removably mounted in openings formed in a holder plate. By providing inserts of this nature, customers could use their own holder plates and form in those plates openings adapted to receive the inserts. The customer could form any number of openings in any desired arrangement. This would allow the customer to readily manufacture holder plates configured to retain essentially any desired arrangement of tools.
Inserts of this nature could be used quite advantageously in a variety of devices. For example, it is anticipated that these inserts would have particular utility in “permanent” (or “continuous”) punch presses. Permanent-type punch presses are well known in the art. These presses characteristically include a plurality of permanently-positioned punch stations, each adapted to perform a given punching or forming operation upon a workpiece that is conveyed sequentially from station to station. While the present invention is by no means limited to use with permanent-type punch presses, embodiments of this nature are expected to have particular advantage.